Influência da germinação na bioacessibilidade e capacidade antioxidante de fitoquímicos de cultivares de trigo duro e mole

Abstract

Wheat (Triticum aestivum L.) is often affected by pre-harvest sprouting (PHS), especially in Brazil, negatively impacting flour quality and the cereal supply chain. However, germination increases the bioaccessibility of phytochemicals in some grains and could be an alternative to improve health benefits and add value to the product. The hypothesis of this study is that wheat cultivars with different grain texture behave differently in relation to changes induced by germination in the content and availability of phytochemicals in the grain. Thus, the objective of this thesis was to evaluate the effect of germination on the profile and content of phytochemical compounds, in addition to the biotransformation, bioaccessibility and antioxidant capacity of phytochemical compounds of wheat during simulated digestion in vitro, comparing a cultivar of soft grain (BRS Guaraim) with another hard texture (BRS Marcante). The work is divided into two studies. Brazilian wheat cultivars were germinated in the laboratory, simulating PHS. In the first study, the phytochemical characterization of wheat cultivars BRS Guaraim and BRS Marcante, from two harvests each, was carried out before and after germination for 24, 48 and 72 hours. In the second study, the influence of germination (72h) on the biotransformation, bioaccessibility and in vitro and in vivo antioxidant capacity of phytochemical compounds of wheat during the simulated digestion of tabbouleh produced with the two cultivars was evaluated. The wheat cultivars with soft and hard texture showed different behavior during germination in terms of changes in phytochemical compounds, with diversification and increase in levels, especially of phenolic compounds linked to the matrix. Germination increased the content of benzoxazinoids and the antioxidant capacity of free phytochemicals in wheat, mainly in the cultivar BRS Marcante. The cultivars also had different behavior in the biotransformation of phytochemicals during digestion and showed differences in the ability to remove different reactive species. Germination increased the rate of bioaccessibility of phytochemical compounds in BRS Guaraim, in addition to increasing the nominal amount of phytochemical compounds available for absorption and present in the fraction that will reach the colon in tabbouleh of both cultivars. Before digestion, BRS Guaraim showed a greater ability to remove peroxyl and hydroxyl radicals (in vitro) than BRS Marcante, but BRS Marcante was more effective in attenuating the intracellular formation of reactive oxygen species (ROS, in vivo). Germination increased peroxyl radical scavenging capacity and decreased hydroxyl radical scavenging capacity and had no effect on ROS removal. Digestion increased the ability to remove peroxyl and hydroxyl radicals and attenuate ROS formation in both cultivars. The results confirm the hypothesis that hard and soft grain wheat cultivars behave differently in relation to phytochemical compounds during germination.